Apparatus for detecting discontinuities in a moving article

ABSTRACT

The invention relates to an apparatus for detecting discontinuities in a moving article, e.g. a punched tape, in which a jet of gas is directed onto one side of the article. If a discontinuity is present, this is detected by a pressure sensitive device, e.g. a diaphragm on the other side of the article which is actuated by the gas jet, to operate an electrical device, e.g. a switch.

United States Patent Inventor Georges Baroin Val De Marne, France Appl, No. 695,456 Filed Jan. 3, 1968 Patented Apr. 27, 1971 Assignee Rhone-Poulenc S. A.

Paris, France Priority Jan. 30, 1967 France 93026 APPARATUS FOR DETECTING DISCONTINUITIES IN A MOVING ARTICLE 7 Claims, 3 Drawing Figs.

US. Cl 200/8l.9, 200/ 83, 200/61.l3 Int. Cl ..II 0 1h 3/24, H0111 35/40 Field of Search ZOO/83.8,

[56] References Cited UNITED STATES PATENTS 2,953,654 9/1960 Bauder 200/46 3,057,974 10/1962 Cohen 200/46 2,251,180 7/1941 Wesley et a1 200/83(.8) 2,337,195 12/1943 Hobbs 200/83(.8) 2,934,618 4/1960 Beller et a1 ZOO/83(9) 3,230,328 1/1966 Chapin ZOO/83(9) Primary Examiner-Robert K. Schaefer Assistant Examiner-J. R. Scott Attorney-Cushman, Darby and Cushman ABSTRACT: The invention relates to an apparatus for detecting discontinuities in a moving article, e.g. a punched tape, in which a jet of gas is directed onto one side of the article. If a discontinuity is present, this is detected by a pressure sensitive device, e.g. a diaphragm on the other side of the article which is actuated by the gas jet, to operate an electrical device, e.g. a switch.

Patented April 27, 1971 2 Sheets-Sheet 1 I nvenlor fim%r Attorney;

APPARATUS FOR DETECTING DISCONTINUITIES IN A MOVING ARTICLE The present invention concerns an apparatus for detecting discontinuities in a moving article.

It is known that it is often necessary to detect slots, perforations or deficiencies in bands during the course of their use. Examples which may be mentioned include paper tapes comprising perforations or slots which are intended to operate mechanical or electrical devices, for example for carrying out the successive instructions of a programme; labels presented in rolls where it is advantageous to be able to detect the transition from one label to another; cinematographic films where slots control light changes and products in band form where it is necessary to detect perforations or material deficiencies. Many other applications could be mentioned wherein it is necessary to detect on a moving band the passage of a perforation or a slot and to bring into action immediately some mechanical or electrical device.

The discontinuities may be a slot formed deliberately on the edge of a product in band form, or a slight interval which may exist between two successive articles (such as for example the gap produced between the cutoff comers of two labels following one another in a printed band, or between two envelopes carried along successively), or perforations of any desired shape situated at a specific zone in a product in band form, or deficiencies(that is to say portions causing distinctly less pressure loss on the passage of a gas flow than the remainder of the band). These slots, perforations or deficiencies" may have been deliberately produced or not.

It is known that this question has already been partly solved by mechanical sensing devices, but these often have too much inertia and are subject to or cause fairly considerable abrasion. Attempts have also been made to use electrical sensing devices, but these also have the disadvantage of contacts which become worn or become fouled. Also electrical or mechanical systems are not suitable for detecting deficiencies."

For detecting such deficiencies it has been proposed to use radioactive detectors, but this gives rise to the dangers of using radioactive products and the regulations covering their use. Photoelectric detection has also been attempted, but this kind of apparatus is delicate, is not any more precise than electrical or mechanical sensing devices, and in many cases may not be suitable.

According to the present invention there is provided apparatus for detecting discontinuities in a moving article, such apparatus comprising a body member having a guide associated therewith for guiding said moving article, a gas jet nozzle on a first side of said body adapted to direct a gas jet against at least a portion of the moving article on said guide, gas pressure sensitive means on a second side of said body opposite said first side in register with said gas jet nozzle and an electrical device associated with said gas pressure sensitive means to be actuated thereby when a gas jet impinges on said gas pressure sensitive means.

The invention will be more easily understood from the following description, given merely by way of example, reference being made to the accompanying drawings, in which:

FIG. 1 shows a sectional view of one embodiment of apparatus according to the invention, and taken on a plane perpendicular to the movement of a band and extending through the axis of the compressed air nozzle;

FIG. 2 shows a perspective view of the apparatus of FIG. 1 from one side; and

FIG. 3 shows a perspective view from the other side.

The apparatus comprises a base 1 which is formed with a guide channel 2 through which a band 3 having notches thereon passes. This band is held in the channel by a transparent plastics material block 4 held by leaf springs 5 and located by four studs 6 and the two abutment bolts 7 on the body member 1. The block 4 carries a gas jet nozzle with a calibrated orifice 8.

Extending through the base is a calibrated orifice 9 situated opposite the nozzle. A circular elastic diaphragm 10 is held in place to extend symmetrically over the end of the orifice 9 remote from channel 2 by a strap 11 fixed to the base 1.

Two parallel leaf springs 12 and 13 are fixed to electrically insulated blocks 14 and 15, secured to the base by bolts 7, the spring 12 carrying a push member 16 which abuts the diaphragm 10 and a contact 17 facing a second contact 18 carried by the spring 13. A micrometer screw 19 on a support 20 regulates the spacing between the two contacts.

In operation of the model described, a paper tape 3 provided with marginal slots passes through the channel at a uniform speed. Compressed air arrives through the nozzle 8, the orifice of which is substantially blocked by the paper tape until a slot is in register therewith.

The jet of air then produced, passes through the calibrated orifice 9 and imparts an impulse to the diaphragm 10 which is deformed and displaces the push member 16 and the spring 12. The contacts 17 and 18 close an electrical circuit which may control any appropriate device.

The sensing device according to the invention has a large number of advantages which make it an especially advantageous piece of apparatus from the industrial point of view:

1. All mechanical sensing devices for detecting slots or perforations have the disadvantage of bearing against the contours of the slots or perforations, and if the material is very thin or if the material is not very strong, damage is caused to the contours explored, since it is necessary for this kind of sensing device to exert a pressure on the contour of the notches, even though this is only a light pressure.

2. The mechanical or electrical sensing devices can easily get out of order, whereas the sensing device according to the invention can always operate regularly.

3. The existing sensing devices may have their operation disturbed by the presence of foreign bodies such as fragments of the material of the travelling band, whereas the apparatus according to the invention automatically eliminates such foreign bodies and can thus operate for a long time without any'failures.

4. The apparatus according to the invention can operate with any form of slots whereas with mechanical or electrical sensing devices the slots must be of an appropriate form.

5. The apparatus according to the invention can detect deficiencies, which neither the mechanical sensing devices nor the electrical sensing devices can detect.

6. The apparatus according to the invention has an extremely short response time, which permits working at a high speed.

7. The apparatus according to the invention can operate in any position without changing the setting, which is not generally possible with mechanical sensing devices.

The advantages mentioned above are those which are generally most important. In many cases there may be others which may encourage selection of the apparatus according to the invention, such as robustness, simplicity in construction, low consumption of fluid, the possibility of operating with a wet band product and many others which may emerge in particular uses.

The description which has been given concerns one preferred embodiment of the invention, but of course there are many technological variants which permit constructing sensing devices constituting other embodiments of the invention. The following may be mentioned more particularly:

The elastic diaphragm, which constitutes a most robust device for detecting the variation in the dynamic pressure of the gas fiow on the passage of a discontinuity may be replaced by any other pressure detecting device such as a folded metal diaphragm, barometric capsule, stress gauge device, piezoelectric device, and in these latter apparatus the electrical contact of course becomes unnecessary.

The electrical contact which is shown in the form of parallel leaf springs with regulation of the contacts, an optionally adjustable, simple and robust device, can be replaced by any other contact system suitable for a particular use. It is sufficient that the device effecting contact can be operated by the detection of the variation in the dynamic pressure. In particular, the electrical contact may equally well be a contact effecting the closing of a circuit on the passage of a discontinuity or a reverse type of contact effecting the opening of a circuit when a discontinuity passes.

The apparatus is constructed in accordance with the usual standards corresponding to this type of device and in accordance with the desired dimensions thereof. The base is advantageously made of metal, the channel of a transparent plastics material such as methyl polymethacrylate, the insulating portions of polyvinyl chloride, methyl acrylate phenol formaldehyde laminate, methyl methacrylate, polyamides such as nylon, polyolefines or polyesters.

The diaphragm is most advantageously made of rubber or silicone elastomer.

The electrical parts are of conventional construction, preferably being made of brass or bronze, the contacts themselves being advantageously constituted by a silver insert.

The band being explored travels over an appropriate guide,

the portion represented as a channel with a slide of transparent plastics material held by leaf springs being possibly replaced by a guide of a size suitable for the band being explored, and the nozzle-orifice assembly has simply to be arranged so that the discontinuities to be detected pass level with them.

In the apparatus described only a single detecting device has been mentioned, but of course several of them could be arranged on the same apparatus so as to constitute a multiple sensing device. This is particularly advantageous when there are several zones to be examined simultaneously or in a specific interval of time.

An advantage of the apparatus resides in the fact that it can operate with air or an optionally chosen gas, such as a chemically inert gas, e.g. nitrogen, and the fluid supply pressure necessary for operating the apparatus can be low. A gas pressure ranging form 50 to 500 millibars is usually satisfactory. The apparatus may of course operate with a higher supply pressure, but this is not advised in most cases. The escape of gas from the nozzle with the calibrated orifice is normally very small, and an increase in pressure causes a continuous gas delivery and a useless consumption as well as creating a noise which may become unpleasant.

The following example describes a sensing device according to the invention.

EXAMPLE The sensing device was intended to detect the passage of marginal slots on a continuous paper tape (thickness 0.08 mm.; width 25 mm.) passing at a speed of 9 meters/minute. The slots were semicircular, mm. in diameter and spaced 36 mm. apart, the slots thus passing at a rate of 250 per minute.

The sensing device corresponded to that shown in FIGS. 1, 2 and 3, the block 4 having an overall dimension of 80 mm. in the direction in which the tape travels and 70 mm. in the perpendicular sense, its thickness being 4 mm. The guide channel 2 was 26 mm. wide and 0.30 mm. deep.

The base was made of brass, the slide of methyl polymethacrylate, the fittings, screws, leaf springs were made of brass, the contacts of silver. The nozzle had an internal diameter of 0.6 mm., the calibrated orifice a diameter of 2.4 mm. The diaphragm was made of rubber 1 mm. in thickness, and the free diameter thereof was 17 mm. The nozzle was supplied with compressed air under a pressure of 100 millibars.

The sensing device regularly effected the detection of the passage of the slots at a rate of 250 per minute, and it operated regularly 9 hours per day with simply one brief clean per week.

lclaim:

1. Apparatus for detecting discontinuities in a moving article, said apparatus comprising, in combination:

a. a body member having a first side and a second side opposite said first side; b. a groove defined in said body member on said first side thereof;

c. a block resiliently urged inwardly toward said body on the first side thereof, to define, with said groove moving article guide means effective to guide said moving article into and out of said body member between said first and second sides;

. gas jet nozzle means on said first side of said body effective to direct the gas jet against at least a portion of said moving article in said guide means;

e. dynamic gas pressure sensitive means on said second side of said body in register with said gas jet nozzle means; and

f. electrical means operatively associated with said dynamic gas pressure sensitive means effective to be actuated thereby.

2. The apparatus defined in claim 1, wherein said gas jet nozzle means is mounted on said block.

3. Apparatus for detecting discontinuities in a moving article, said apparatus comprising, in combination:

a. a body member having a first side and a second side opposite said first side;

b. moving article guide means associated with said body member efi'ective to guide said moving article into and out of said body member between said first and second sides;

c. gas jet nozzle means on said first side of said body effective to direct the gas jet against at least a portion of said moving article in said guide means;

d. means defining an opening through said body in register with said gas jet nozzle means;

e. dynamic gas pressure sensitive means on said second side of said body in register with said opening and said gas jet nozzle means; and

f. electrical means operatively associated with said dynamic gas pressure sensitive means effective to be actuated thereby.

4. The apparatus defined in claim 3, wherein said dynamic gas pressure sensitive means comprise an elastic diaphragm secured to said second side of said body to extend over said opening and a push member abutting said diaphragm effective to be pushed by said diaphragm upon flexure of the latter under the action of a gas jet from said nozzle.

5. The apparatus defined in claim 4, wherein said electrical means includes an electrical switch operated by said push member.

6. The apparatus defined in claim 5, wherein said electrical switch includes first and second leaf springs carried by said body member and electrically insulated from one another, and first and second contacts carried by said first and second leaf springs respectively, said first leaf spring being in abutting relation to said push member.

7. The apparatus defined in claim 6, wherein the position of said second contact is adjustable. 

1. Apparatus for detecting discontinuities in a moving article, said apparatus comprising, in combination: a. a body member having a first side and a second side opposite said first side; b. a groove defined in said body member on said first side thereof; c. a block resiliently urged inwardly toward said body on the first side thereof, to define, with said groove moving article guide means effective to guide said moving article into and out of said body member between said first and second sides; d. gas jet nozzle means on said first side of said body effective to direct the gas jet against at least a portion of said moving article in said guide means; e. dynamic gas pressure sensitive means on said second side of said body in register with said gas jet nozzle means; and f. electrical means operatively associated with said dynamic gas pressure sensitive means effective to be actuated thereby.
 2. The apparatus defined in claim 1, wherein said gas jet nozzle means is mounted on said block.
 3. Apparatus for detecting discontinuities in a moving article, said apparatus comprising, in combination: a. a body member having a first side and a second side opposite said first side; b. moving article guide means associated with said body member effective to guide said moving article into and out of said body member between said first and second sides; c. gas jet nozzle means on said first side of said body effective to direct the gas jet against at least a portion of said moving article in said guide means; d. means defining an opening through said body in register with said gas jet nozzle means; e. dynamic gas pressure sensitive means on said second side of said body in register with said opening and said gas jet nozzle means; and f. electrical means operatively associated with said dynamic gas pressure sensitive means effective to be actuated thereby.
 4. The apparatus defined in claim 3, wherein said dynamic gas pressure sensitive means comprise an elastic diaphragm secured to said second side of said body to extend over said opening and a push member abutting said diaphragm effective to be pushed by said diaphragm upon flexure of the latter under the action of a gas jet from said nozzle.
 5. The apparatus defined in claim 4, wherein said electrical means includes an electrical switch operated by said push member.
 6. The apparatus defined in claim 5, wherein said electrical switch includes first and second leaf springs carried by said body member and electrically insulated from one another, and first and second contacts carried by said first and second leaf springs respectively, said first leaf spring being in abutting relation to said push member.
 7. The apparatus defined in claim 6, wherein the position of said second contact is adjustable. 